Improvement in photographic lenses



J. SCHNITZER.

Photographic Lens.

No. 49,160. Patented Aug. 1, 1865.

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UNITED STATES PATENT OFFICEo JOSEPH SOHNITZER, OF NEW YORK, N. Y.

IMPROVEMENT IN PHOTOGRAPHIC LENSES.

Specification forming part of Letters Patent No. 119, 160, dated August l, 1365.

To all whom it may concern:

Be it known that I, J osEPE SoHNiTzER, of the city, county, and State of New York, have invented a new and Improved Photographic Lens; and I do hereby declare that the following is a full, clear, and exact description thereof, which will enable those skilled in the art to make and use the same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure l represents a longitudinal central section ot' this invention. Fig. 2 is a horizontal section of the same in the plane indicated bythe line w x, Fig. 1. Fig. 3 is a similar section of the same, the plane of section being indicated by the line y y, Fig. l.

Similar letters of reference indicate corresponding parts.

The object of this invention is a photographic lens which combines with a short focus an angle of eighty degrees, more or less, and which is so arranged that its focus can bc adjusted and that the sameinstrument can be used for pictures of different size.

The lens A is composed of a triplet front lens, B, and doublet back lens, O. The front lens is constructed of two pieces of crown-glass and one of hint-glass. The two crown-glasses a b are meniscus-shaped, and the flint-glass c tits with one surface to the concave side of the first crown-glass and with its other concave side to the convex side of the second crownglass, as shown in Fig.1 ofthe drawings. The several glasses are cemented together in the usual manner.

The correcting back lens, O, of the instrument. is made of a negative flint-glass, d, and a double-convex crown-glass lens, e. The first surface of the dint-glass d next the front lens is slightly concave, and the other surface is also concave, but with a much shorter radius than the tirst. The crown-glass lens e has two convex sides with different radii, the side with the longest radius being turned inside, and the other side with the shortest radius being outside.

'lhe outside surface of the front lens is of a shorter radius than the outside surface of the vback lens.

separated by a ring, f, which represents a correcting-distance, but which is not absolutely necessary. rEhe radii of the Hint-glass surface facing the crown-glass e, and of the crownglass surface facing the flint-glass d, are different, thc radius of the dint-glass surface being the shorter.

The two lenses B G are separated from each other by the center piece, E, which is arranged about in the middle between both outside glass surfaces of the instrument. It consists of two revolving disks, F Gr, each with holes of' different sizes. The disk F,facing the front lens, is furnished with three holes,g 7i i, two of which are tilled with glasses, both of the same shape, but unequal negative focal length. Their form is convex-concave, the convex side being turned against the front lens.

The rotary diaphragm G has four holes7 k l 1n, of different diameters corresponding with the optical axis of the instrument. Both these Y rotary disks are so arranged that they can be easily handled from the outside ofthe instrument, and they are provided with small springcatches, a, to keep them truc inthe axis ofthe instrument.

By the lenses 7L i in the disk F the focus of the instrument can be changed and pictures of different size can be produced with the same instrument.

My new instrument is adapted for a portrait apparatus as well as for a view-lens. It has an angle of eighty degrees (more than any instrument known tome, with the exception of my globelens,)and it has a short focus, so that the photographer is enabled to work in a small room. The picture or portrait can be made large or small,as maybe desired. For groups my instrument will be particularly fine. Its greatdepth enables a person to select aposition without the aid of the photographer.

rEhe lenses in the disk F render my instrument particularly tit for views of landscapes, &c. By turning said disk pictures of three dit'- ferent sizes can be produced. Vhen the free hole g is in the center thefocusis shortest. By turningthe first lens,h, in the center the focus is lengthened, and by the negative property ot' this lens the field for the lengthened focus is corrected. The second lens, ,has the same property, but the focus of the instrument is still further lengthencd. The difference between the in and out side radii of these negative lenses is so little that it doesnotinterfere with the aohromatismmnd i'or this reason singlelenses can beemployed. If desired, the nurnber of lenses in the disk F can he still further increased.

Ielaim as new and des-ire to secure by Letters Patentl. A lens, A, constructed of a triplet front lens, B, and doublet back lens, (l, substanstantially as herein set forth. 

